1. Field of the Invention
This invention relates to devices used in the manufacture of nonwoven sheeting and, specifically, to devices known as crosslappers which provide a means for transferring filaments or fleece from a feed means such as a carding machine to a delivery means such as a laydown machine in such a way that the laydown machine receives a web of uniform thickness and density and, if desired, of modified weight basis and width.
2. Description of the Prior Art
U.S. Pat. No. 3,877,628, issued Apr. 15, 1975 on the application of Asselin et al., discloses a crosslapper having a certain guide belt arrangement to minimize disruption of the fleece by air flow during high speed operation of the device. That patent recognizes the difficulty of eddies of air which blow the fleece and disrupt the web in high speed operation, and attempts to improve the situation by carrying the fleece between two closely-positioned guide belts prior to the fleece transfer. There is no mention of the construction of guide belts used therein.
U.S. Pat. No. 3,558,029, issued Jan. 26, 1971 on the application of Manns, discloses a crosslapper in which a carded web is advanced by being positively held between conveyer belts. This arrangement is said to deposit the web evenly and without formation of folds. It is said that the conveyer belts can be formed from continuous fabrics made from synthetic material.
British Pat. No. 1,527,230, published Oct. 4, 1978 on the application of Jowett, discloses a modified crosslapper wherein there is provision for the lattices or conveyer belts to operate at variable speeds throughout each cycle. There is no mention of the kind or construction of the conveyer belts.
U.S. Pat. No. 3,851,681, issued Dec. 3, 1974 on the application of Egan, U.S. Pat. No. 4,376,455, issued Mar. 15, 1983 on the application of Hahn, and U.S. Pat. No. 4,408,637, issued Oct. 11, 1983 on the application of Karm, disclose woven fabrics useful as the support belt for papermaking processes.
U.S. Pat. No. 4,379,735, issued Apr. 12, 1983 on the application of MacBean, discloses a particular construction of woven fabric for use on so-called "twin wire" paper making machines.
In the field of airlay crosslappers, it has been customary for fleece transporting belts to be made from impermeable material and, as can be seen from the references discussed above, it has been customary to minimize the effects of air eddies in the lay-down by means of sandwiching the fleece between two belts. In the field of papermaking machines, it has been customary to use foraminous screens to strain water from the so-called "furnish" during wetlay. Crosslappers and papermaking machines are from entirely different fields and references from one field do not suggest any application in the other field. Nevertheless, the present invention relates to crosslappers utilizing fleece transporting belts made from foraminous fabrics with significant void fraction.